Method for checking and/or monitoring the leak tightness of a plurality of pneumatically or hydraulically actuated actuators and machine, in particular medical treatment machine

ABSTRACT

The present invention relates to a method for checking and/or monitoring the leak tightness of a plurality of pneumatically or hydraulically actuated actuators of a machine, in particular a plurality of valve actuators of a medical treatment machine, wherein pressure is exerted on the actuators in different combinations during the operation of the machine, wherein the common pressure drop occurring during a stationary operating phase at the actuators on which pressure is exerted in the respective combination is measured for a plurality of different combinations of actuators on which pressure is exerted, and wherein a respective leak tightness value is determined for individual actuators and/or groups of actuators with the pressure drop which is measured for those combinations and in which the respective actuator and/or the respective group of actuators on which pressure is exerted being taken into said leak tightness value. The invention furthermore includes a machine, in particular a medical treatment machine, having a corresponding valve actuator monitoring.

The present invention relates to a method for checking and/or monitoringthe leak tightness of a plurality of pneumatically or hydraulicallyactuated actuators of a machine, in particular a plurality of valveactuators of a medical treatment machine, as well as to a machine, inparticular a medical treatment machine, having a control for thecarrying out of the corresponding methods.

The present invention in particular relates to a method for checkingand/or monitoring the leak tightness of a plurality of pneumatically orhydraulically actuated actuators of a machine in which a cassette systemis used for the transport of liquids, in particular medical liquids. Themethod in accordance with the invention can be used particularlyadvantageously in the area of dialysis, in particular of peritonealdialysis, in particular in treatment machines having a cassette systemfor the transport of the treatment liquids or for the carrying out ofthe treatment. The method can equally be used in hemodialysis or ininfusion systems.

The present invention in particular relates to peritoneal dialysismachines such as are presented in US 2007/0112297 A1 and US 2006/0195064A as well as to methods for the operation of such peritoneal dialysismachines. The full extent of the content of 2007/0112297 A1 and US2006/0195064 A1 is hereby an integral part of the disclosure of thepresent application.

The pneumatically or hydraulically actuable actuators of the machine areadvantageously valve actuators with which the valves used in thesecassette systems are switched. The cassettes are made as disposablearticles and have valve points on which the valve actuators of themachine act and thus switch the valves. The cassettes in particular haveliquid conducting passages which have at least one flexible wall in theregion of the valve points which can be pressed into the liquidconducting passage by the valve actuator and thus block said passage. Inthis connection, the actuators advantageously have a flexible regionwhich expands when pressure is exerted on the actuator and thus acts asa valve tappet. Hydraulically or pneumatically actuable pistons canequally be used as actuators which advantageously likewise serve asvalve tappets. In such cassette systems, the region advantageously atthe cassette side for the conveying of the process liquid such as thedialysate is separated by at least one membrane from the regionadvantageously at the machine side on which pressure is exerted for theactuation of the actuators.

During ongoing operation of the machine, different switching patterns ofthe valves are run through to provide the liquid paths required in thecassette e.g. during a purging process or during a treatment. Theactuators of the machine have pressured exerted on them for this purposeduring the ongoing operation of the machine in different combinations inorder thus to switch the corresponding valves in the cassetteaccordingly and to provide the desired fluid paths for the operation ofthe cassette.

The actuators usually have an active switching state in which pressureis exerted on them and an inactive switching state in which pressure isnot exerted on them. It is possible to switch to and fro between thesestates by exerting pressure on the actuators or removing the pressure.During such switching processes, the pressure applied to the systemchanges, whereas a stationary state is adopted between the switchoverprocesses in which the pressure applied to the actuators on whichpressure is exerted being substantially constant. However, withpneumatically or hydraulically actuable actuators leaks can occur on theside on which pressure is exerted.

In known methods for checking and/or monitoring the leak tightness ofsuch actuators, an initial test is therefore usually carried out at thestart of the treatment in which test pressure is exerted on theactuators and the pressure drop per time unit is measured in thesubsequent stationary state to determine any leaks. If the pressure dropper time unit exceeds a certain limit value in this connection, theoperation of the device is not released.

A leak present on the initialization of the device can admittedly berecognized with such a method. However, there is no longer anypossibility to determine whether a leak has arisen in the system duringthe operation of the device. In particular no initial test can becarried out during the operation of the machine since the machine wouldhave to be stopped completely for this purpose. Furthermore, there is noindication of when a suitable time for such a test during the treatmentwould be. Leaks in the actuators can, however, particularly arise duringthe ongoing treatment due to wear of the actuators.

It is therefore the object of the present invention to provide a methodfor checking and/or monitoring the leak tightness of a plurality ofpneumatically or hydraulically actuated actuators which can be carriedout during the ongoing operation of the machine. It is furthermore theobject of the present invention to provide a machine, in particular amedical treatment machine, having corresponding valve actuatormonitoring.

This object is solved in accordance with the invention by a method inaccordance with claim 1 and a machine in accordance with claim 20.Advantageous aspects of the invention form the subject of the dependentclaims.

In this connection, the invention includes a method for checking and/ormonitoring the leak tightness of a plurality of pneumatically orhydraulically actuated actuators of a machine, in particular of aplurality of valve actuators of a medical treatment machine, withpressure being exerted on the actuators in different combinations duringoperation. In accordance with the invention, the pressure drop occurringduring a stationary operating phase at the actuators on which pressureis exerted in the respective combination is measured together for aplurality of different combinations of actuators on which pressure isexerted. For individual actuators and/or individual groups of actuators,a leak tightness value is then respectively determined into which apressure drop is taken which is measured for those combinations in whichpressure is exerted on the respective actuator and/or the respectivegroup of actuators.

The machine in accordance with the invention exerts pressure on theactuators in different combinations during its operation to switch thevalves on the cassette side and thus to establish the desired liquidpaths. Switching operating phases hereby result in which switching takesplace between different combinations of actuators on which pressure isexerted so that the system pressure fluctuates and stationary operatingphases which are disposed therebetween and in which a substantiallyconstant system pressure is applied to a fixed combination of actuatorswhich is not changed by switchover processes and which can only reduceover time due to the leak of the system. The pressure drop in thesestationary operating phases is therefore a measure for the leaktightness of the actuators on which pressure is just being exerted.

During these stationary operating phases, the pressure now respectivelyapplied at all actuators together on which pressure is exerted ismeasured and the pressure drop is measured which arises during thesestationary operating phases. The pressure drop is advantageouslymeasured for the time period in which there is a correspondingcombination. The pressure applied at all actuators together on whichpressure is exerted can in particular be measured at two differentpoints in time during the stationary operating phase, in particular atthe start and at the end of the stationary operating phase and thepressure drop can be determined from the difference of the two values.On a switchover process, the pressure drop measured is thenadvantageously supplied to an evaluation unit and is advantageouslystored in a table.

An individual measurement of the pressure drop for only a combination ofactuators on which pressure is exerted usually does not allow anyreliable conclusions on the leak tightness of individual actuatorsand/or individual groups of actuators since a plurality of actuatorsusually have pressure exerted on them simultaneously in such acombination and the measured pressure drop thus forms a collective valuefor the sum of all leaks of the participating actuators.

Now, however, a leak value for individual actuators and/or individualgroups of actuators can also be determined from the data for a pluralityof different combinations of actuators on which pressure is exerted. Inthis connection, the pressure drop measured for a specific combinationis taken into the leak tightness value of a specific actuator if thisactuator had pressure exerted on it in this combination. If, incontrast, an actuator did not have pressure exerted on it in a specificcombination, the pressure drop measured during this combination is nottaken into the leak value of this actuator.

A trend for an actuator or for a group of actuators can thus bedetermined from the values collected thereby, at least after a specifictime or frequency of the measurements. Although usually pressure isexerted on a plurality of actuators simultaneously during the usualongoing operation of the machine, the leak tightness of every individualactuator can thus be evaluated by the collection of values from aplurality of different combinations. In accordance with the invention,the fact is utilized in this connection that pressure is anyway exertedon a plurality of different combinations of actuators in the operationof the machine. An estimate of the leak tightness of the individualactuators can thus be gained by evaluation of the pressure drop forthese different combinations.

The respective measurement time during which the pressure drop occurredis advantageously taken into the leak tightness value in addition to thepressure drop. In the method in accordance with the invention, inaddition to the pressure drop occurring for the respective combination,the measuring time during which this pressure drop occurred canaccordingly also be taken into account. For this purpose, the pressuredrop and the measuring time are advantageously transmitted to anevaluation unit for the respective stationary operating phase. Since thepressure drop occurring during a stationary operating phase also dependson the measuring time in addition to the leak of the respectiveactuators on which pressure is exerted, a more precise detection ofleaks is possible by the taking into account of these measuring times.

In this connection, a pressure drop per time unit formed from the commonpressure drop values and the measuring times can in particular be takeninto the leak tightness value. The pressure drop per time unit forms arelatively precise measure for the leak tightness of the respectiveactuators in this connection.

Advantageously, for the determination of the leak tightness value of anindividual actuator and/or of an individual group of actuators, a meanvalue is formed into which the pressure drop and advantageously themeasuring time for all those combinations of actuators on which pressureis exerted are taken in which pressure was exerted on the respectiveactuator and/or the respective group of actuators. A mean value istherefore formed for the determination of the leak tightness value of aspecific actuator from all those measured values for the pressure dropwhich were measured in operating phases in which pressure was exerted onthis specific actuator. Although every single actuator has, as the casemay be, only caused a specific portion of the pressure drop itself inthese operating phases, whereas another portion of the pressure drop wascaused by further actuators on which pressure was likewise exerted, avalue for the leak tightness results for every single actuator in arelatively good approximation by this averaging over a plurality ofdifferent combinations of actuators. In this connection, the measuringtimes for the respective pressure drop are also respectively taken intothe mean value formation, with a mean value of the measured pressuredrop per time unit in particular being able to be formed.

In this connection, for the determination of the leak tightness value ofan individual actuator and/or of an individual group of actuators, theoptionally weighted mean value of the pressure drop and/or of thepressure drop per time unit of all those combinations of actuators onwhich pressure is exerted is/are advantageously calculated in whichpressure is exerted on the respective actuator or the respective groupof actuators.

The optionally weighted mean value formation can take place in differentmanners. In this connection, in particular all the combinations in whichpressure was exerted on an actuator can be weighted equally so that thepressure drop and/or the pressure drop per time unit measured for aspecific combination is taken into the mean value formation for the leakvalue of the participating actuators independently of the duration andof the number of the actuators on which pressure is exerted.

However, advantageously, the duration of the stationary operating phasesin which the pressure drop and/or the pressure drop per time unit wasmeasured is taken into the mean value formation. In this connection, inparticular the time mean value of the pressure drop per time unitmeasured during all the stationary operating phases in which pressurewas exerted on this actuator can be formed for the leak tightness valueof a specific actuator. Combinations which are present over a longerperiod are hereby weighted more than combinations which are onlyswitched for a brief time. With combinations with longer stationaryoperating phases, however, the measured values for the pressure drop pertime unit are also more precise so that the precision hereby increases.

In this connection, for the determination of the leak tightness value ofan individual actuator and/or of an individual group of actuators, thesum of the pressure drops and the sum of the measuring times for allthose combinations of actuators on which pressure is exerted areadvantageously determined at which pressure is exerted on the respectiveactuator and/or on the respective group of actuators. A mean pressuredrop per time unit can then be determined from the quotient of these twosums which is taken into the leak tightness value of the actuator and/orof the group of actuators.

Furthermore, the number of the actuators on which pressure is exerted ina specific combination can advantageously be taken into the mean valueformation. In this connection, the pressure drop determined for aspecific combination can in particular be taken the less into the leaktightness values of the participating actuators, the more actuators hadpressure exerted on them. It is hereby prevented that combinations witha large number of actuators on which pressure is exerted and in whichcorrespondingly high common pressure losses occur are included overproportionally in the mean value formation.

Alternatively, however, provision can also be made that the commonpressure drop measured for a specific combination of actuators on whichpressure is exerted is taken into the mean value formation independentlyof the number of the actuators on which pressure is exerted in thiscombination. The leak tightness values associated with an actuator witha high leak rate is hereby not reduced in that this actuator is operatedtogether in combination with other actuators which have a substantiallylower leak rate. Accordingly, defective actuators can be recognizedparticularly easily by such a combination, but also the values of theactually correctly working actuators.

Further advantageously, in accordance with the invention, the commonpressure drop for all actuators on which pressure is exerted in therespective combination and measured for a specific combination ofactuators on which pressure is exerted is taken into the leak tightnessvalue of said actuators in equal amounts. Such a uniform distribution ofthe values is in particular meaningful when all actuators have anidentical structure.

Further advantageously, in accordance with the invention, the leaktightness values of the individual actuators and/or of individual groupsof actuators are updated continuously during the operation of themachine. The leak tightness values of the individual actuators and/or ofindividual groups of actuators are in particular advantageously updatedwhen the machine switches over from one combination of actuators onwhich pressure is exerted into another combination. The pressure drop orthe pressure drop per time unit measured during the stationary operatingphase of the previous combination is then advantageously used for theupdating of the leak tightness values of the individual actuators and/orof the individual groups of actuators, whereas a new pressuremeasurement is started on the reaching of the stationary operating phaseof the new combination.

For the checking and/or monitoring of the actuators, the range of thespecific leak tightness values is advantageously used in the method inaccordance with the invention. In this connection, the lowest leaktightness value is compared with the highest leak tightness value andthus the range of the leak tightness values over all actuators isdetermined. A low range is an indicator for a high leak tightness of theactuators, whereas a high range is an indicator for a leak sinceevidently at least one actuator is present which has a substantiallydifferent leak tightness value than the remaining actuators.

Further advantageously, the sum of all the determined leak tightnessvalues is used for the checking and/or monitoring of the actuators. Thissum also permits a global statement on the leak tightness of the system.

Further advantageously, the change over time of the determined leaktightness values is used for the checking and/or monitoring of theactuators. It can hereby be determined whether pronounced changes in theleak tightness occur with individual actuators or individual groups ofactuators.

A leak can thus be recognized during the ongoing operation of themachine by evaluating the corresponding leak tightness values. Theongoing operation is advantageously stopped and a test carried out on arecognition of a leak. It can now again be ensured by such a test thatthe values determined during the ongoing operation do not represent anincorrect measurement, but that a leak is actually present.

In this connection, an initial test can be carried out as the test inwhich all the actuators are checked. Such an initial test routine isalready provided with known devices and is initially carried out beforethe putting into operation.

Alternatively, a test can also be carried out in which only theindividual actuator and/or the individual group of actuators is checkedin which a leak was recognized. A fast check of the leak determinedduring the ongoing operation is hereby possible. If the leak is notconfirmed in the individual actuator or in the individual group ofactuators, an initial test can still be carried out as required to checkwhether a leak is present in other actuators.

Further advantageously, on the recognition and/or confirmation of aleak, the leaking actuator is not further used or the machine is putinto a secure state. Since a number of fluid paths can be provided in acassette by switching different actuators, it is possible not to actuateindividual actuators during the ongoing operation and nevertheless tocontinue to operate the machine. In accordance with the invention,actuators recognized as leaking can therefore be shut down withoutimpairing the safety of the cassette. If this is not possible, themachine, in contrast, switches into a safe state until a repair has beenmade.

Generally, when a leak was recognized, safety measures can then beinitiated. An alarm can in particular also be triggered in thisconnection.

Advantageously, the machine in accordance with the invention is used forthe control of the valves of a cassette for the transport of a medicalliquid, in particular in dialysis. Such cassettes usually have liquidconducting passages which have at least one flexible wall in the regionof the valve points which is pressed into the passages to block them.The liquid conducting passages are in particular covered via a flexiblemembrane. By pressing this membrane into the liquid conducting passages,they can then be blocked so that valves are produced. The actuators inaccordance with the invention advantageously work as valve tappets topress the flexible wall or membrane into the liquid conducting passages.An actuator in accordance with the invention can in particular have aflexible region which expands on the application of pressure and is thuspressed into the liquid conducting regions of the cassette.

The present invention furthermore includes a machine, in particular amedical treatment machine, having a plurality of pneumatically orhydraulically actuable actuators, in particular a plurality of valveactuators, and having a pressure measuring device for the measurement ofthe pressure applied together to the actuators on which pressure isexerted as well as having an electronic control for the carrying out, inparticular the automatic carrying out, of a method such as was describedabove. The electronic control in accordance with the inventionadvantageously has a correspondingly designed computing unit as well asa memory for the storage of the leak tightness values. The sameadvantages obviously result from such a machine which were presentedfurther above with respect to the method. The machine can in particularcarry out the method in accordance with the invention for checking ormonitoring the leak tightness of the actuators of the machineautomatically during the ongoing operation of the machine so that thesafety of operation is increased.

Advantageously, the machine is a machine for the control of the valvesof a cassette for the transport of a medical liquid, and indeed inparticular a machine for use in dialysis, in particular in peritonealdialysis. The cassette is inserted into such a machine as a disposableelement and serves the transport of a medical liquid, e.g. of thedialysate. The actuators in accordance with the invention are thencoupled to the cassette and are used as valve actuators for the controlof the valves of the cassette.

The present invention thus includes a machine, in particular a medicaltreatment machine, having a plurality of pneumatically or hydraulicallyactuable actuators, in particular a plurality of valve actuators, havinga pressure measuring device for the measurement of the pressure appliedto the actuators together on which pressure is exerted, and having anelectronic control which controls the actuators and the pressuremeasuring device such that the actuators have pressure exerted on themin different combinations during the operation of the machine and thecommon pressure drop occurring during a stationary operating phase atthe actuators on which pressure is exerted in the respective combinationis measured for a plurality of different combinations of actuators onwhich pressure is exerted. The machine furthermore includes anevaluation unit which in each case determines a leak tightness value forindividual actuators and/or individual groups of actuators, with thepressure drop measured for those combinations in which pressure isexerted on the respective actuator and/or the respective group ofactuators being taken into said leak tightness value. Furthermore, achecking and/or monitoring unit is provided which checks and/or monitorsthe leak tightness of the actuators of the machine based on the leaktightness values determined. The machine in accordance with theinvention also thus has the possibility of continuously monitoring theleak tightness of the pneumatically or hydraulically operated actuatorsduring ongoing operation without the operation of the machine having tobe interrupted for this purpose.

Advantageously, in addition to the pressure drop, the respectivemeasuring time during which the pressure drop occurred is taken into theleak tightness values formed by the evaluation unit. Since the pressuredrop which occurs during a stationary operating phase at the actuatorson which pressure is exerted together in the respective combination is,in addition to the leaks of the actuators on which pressure isrespectively exerted, also dependent on the measuring time during whichthe pressure drop is determined, a more precise determination of theleak tightness values thus results. The pressure can in particular bemeasured during two different times of a stationary operating phase andthe pressure drop hereby determined can be transferred to the evaluationunit together with the time period between the two times. A memory canlikewise be provided in which these values or values calculatedtherefrom are stored.

Advantageously, a pressure drop per time unit formed from the measuredpressure drop values and from the measuring times is taken into the leaktightness value. The pressure drop per time unit is a relatively precisemeasure for the leak tightness of an actuator and/or an individual groupof actuators. In this connection, both the respective pressure drop pertime unit measured for the different combinations of actuators on whichpressure is exerted can be taken into the evaluation and/or a meanpressure drop per time unit can be determined from the measured pressuredrop values and the measuring times for a plurality of combinations.

Advantageously, the evaluation unit forms a mean value for thedetermination of the leak tightness value of an individual actuatorand/or of an individual group of actuators and the pressure drop andadvantageously the measuring time for all those combinations ofactuators on which pressure is exerted is taken into said mean value atwhich pressure was exerted on the respective actuator and/or therespective group of actuators. A good approximation to the actual leaktightness value of the respective actuator or the respective group ofactuators thus results from the mean value formation over the measuredvalues for all the combinations in which pressure is exerted on aspecific actuator or a specific group of actuators.

Advantageously, the evaluation unit calculates the leak tightness valueof an individual actuator and/or of an individual group of actuators asthe optionally weighted mean value of the pressure drop and/or of thepressure drop per time unit of all those combinations of actuators onwhich pressure is exerted in which pressure is exerted on the respectiveactuator and/or the respective group of actuators. The weighting of themeasured values for the pressure drop and/or the pressure drop per timeunit for the respective combination of actuators on which pressure isexerted can take place in different manners.

The duration of the stationary operating phases for which the pressuredrop and/or the pressure drop per time unit was determined can inparticular be taken into the mean value formation. In particular when amean value of the measured pressure drops per time unit is formed, thatis when the measuring times are anyway taken into the leak tightnessvalues, the duration of the stationary operating phases or the measuringtimes can be taken into the mean value formation in addition thereto.The temporal mean value can in particular be formed.

Furthermore, the number of the actuators in which pressure is exerted ina specific combination can be taken into the mean value formation.Alternatively to this, the measured common pressure drop for a specificcombination of actuators on which pressure is exerted can go into themean value formation independently of the number of the actuators onwhich pressure is exerted in this combination. Leaking actuators arehereby easier to recognize, but also influence the leak tightness valuesof actually leak tight actuators more.

Advantageously, the common pressure drop for all the actuators on whichpressure is exerted measured for a specific combination of actuators onwhich pressure is exerted is taken into account in the leak tightnessvalue of said actuators in equal amounts. The reasons for this procedureare that the system has no more detailed information on how a commonpressure drop of a plurality of actuators on which pressure is actuatedis due to the individual actuators. Due to the use of measured values ofa plurality of different combinations of actuators, a relatively goodapproximation to the actual leak tightness of the individual actuator orof the group of actuators nevertheless results over time for eachindividual actuator or for each specific group of actuators.

Advantageously, for the specific implementation of the method inaccordance with the invention, the evaluation unit for the determinationof the leak tightness values of an individual actuator and/or anindividual group of actuators can determine the sum of the pressuredrops and the sum of the measuring times for all those combinations ofactuators on which pressure is exerted in which pressure was exerted onthe respective actuator and/or the respective group of actuators. A meanpressure drop per time unit can then be formed for each actuator foreach group of actuators from this sum of the pressure drops and this sumof measuring times and the leak tightness value of the respectiveactuator or the respective group of actuators in turns results from saidmean pressure drop per time unit. Such a procedure corresponds to theformation of the temporal mean value over the pressure drop per timeunit of all those combinations of actuators on which pressure is exertedand in which pressure is exerted on the respective actuator and/or therespective group of actuators.

Further advantageously, in accordance with the invention, the evaluationunit updates the leak tightness values of the individual actuatorsand/or individual groups of actuators continuously during the operationof the machine. A reliable checking and/or monitoring of the leaktightness of the actuators hereby results.

The checking and/or monitoring unit advantageously checks and/ormonitors the leak tightness of the actuators on the basis of the rangeof the leak tightness values determined. A high range of leak tightnessvalues is an indicator of a leaking actuator, whereas a low range is anindicator for the leak tightness of all actuators.

Further advantageously, the checking and/or monitoring unit checksand/or monitors the leak tightness of the actuators based on the sum ofall leak tightness values determined. This sum of all determined leaktightness values is a value which corresponds to the total leaktightness of the system.

Further advantageously, the checking and/or monitoring units of themachine in accordance with the invention checks and/or monitors the leaktightness of the actuators based on the change over time of the leaktightness values determined. Such a change in the determined leaktightness values can be an indicator for the occurrence of such a leak.

Obviously, in this connection, a combination of a plurality of valuescan also be used for checking and/or monitoring the leak tightness ofthe actuators.

Further advantageously, the checking and/or monitoring unit stops theongoing operation of the machine and carries out a test on therecognition of a leak. By this test, the leak tightness of a specificactuator or of a specific group of actuators determined during theongoing operation can be checked or confirmed again e.g. by the checkingand/or monitoring unit by this test.

In accordance with the invention, an initial test can be carried out inwhich all actuators are checked. Alternatively, however, a test can becarried out in which an individual actuator and/or an individual groupof actuators are checked in which a leak was recognized. All theactuators no longer have to be checked since initially, for theconfirmation of the leak, a check of the actuator or group of actuatorsis sufficient in which the checking and/or monitoring unit hadrecognized the leak.

Advantageously, the control of the machine in accordance with theinvention no longer uses the leaking actuator on a recognition and/orconfirmation of a leak. The control can in particular continue theoperation of the machine if this is possible while bypassing the leakingactuator. Otherwise, the machine switches into a safe state.

Advantageously, the machine in accordance with the invention is used forthe control of the valves of a cassette for the transport of a medicalliquid, in particular for use in dialysis. In this connection, thecassette usually forms a disposable part which is inserted into themachine, with the machine controlling the liquid flows in the cassette.

Advantageously, the machine in accordance with the invention has acoupling surface to which a cassette for the transport of a medicalliquid can be coupled, with the actuators being arranged at the couplingsurface. The actuators at the machine side can thus engage onto thevalves of the coupled cassette and thus provide different fluid paths inthe cassette.

The present invention further advantageously includes a computer programproduct, in particular a storage medium with a computer program, inparticular for transfer to a machine, with commands for the carrying outof a method such as was described above. The same advantages as weredescribed with respect to the method also result from such a computerprogram product. Such a computer program stored on a storage medium canin particular be transferred to an existing machine to carry out themethod in accordance with the invention there for checking and/ormonitoring the leak tightness of the actuators of the machine. Existingmachines can hereby be retrofitted with the method in accordance withthe invention. This is in particular possible without problem in that noadditional components are required to carry out the method.

The present invention will now be described in more detail withreference to an embodiment and to the drawings. There are shown:

FIGS. 1-4: different combinations of actuators on which pressure isexerted during the operation of a machine in accordance with theinvention.

The present invention will now be presented in more detail withreference to an embodiment in which the method in accordance with theinvention for checking and/or monitoring the leak tightness of aplurality of pneumatically actuable valve actuators of a medicaltreatment machine is used.

Disposable cassettes are usually used in such medical treatment machinesfor the transport of medical liquids. These disposable cassettes haveliquid passages which are covered by a flexible foil. The disposablecassette is inserted into the treatment machine in this connection andis coupled to a coupling surface at the device side such that theactuators arranged in the coupling surface of the treatment machine canpress the flexible foil of the cassette into the liquid conductingpassages and thus determine the fluid paths in the cassette. Thepneumatically actuated actuators advantageously have flexible regionswhich expand on the application of pressure to the actuator and thuspress the flexible foil into the liquid conducting passages. Pumps andthe like can hereby also be realized in addition to valves.

In this connection, during the ongoing operation of the treatmentmachine, pressure is alternatively exerted on different combinations ofactuators in order to establish correspondingly different fluid paths inthe cassette. In this connection, typically pressure is exertedsimultaneously on a plurality of valves in each combination so that thepressure loss which occurs on all valves together on which pressure isexerted during a specific combination cannot be associated with anindividual valve. To check the leak tightness of the individualactuators of the treatment machine in accordance with the invention, themethod in accordance with the invention is now used which is carried outduring the normal operation of the treatment machine. It is possiblewith the method in accordance with the invention to associate acorresponding leak tightness value to every single actuator by the useof data from a plurality of different combinations of actuators on whichpressure is exerted.

In this connection, the pressure drop which initially occurs during astationary operating phase at the actuators on which pressure is exertedtogether in the respective combination for a plurality of differentcombinations of actuators on which pressure is exerted is measured andis stored together with the measuring time. A respective leak tightnessvalue is now determined from these data for individual actuators and/orindividual groups of actuators and the pressure drop or the pressuredrop per time unit measured for those combinations in which pressure isexerted on the respective actuator and/or the respective group ofactuators is taken into said lead tightness value.

The course of the operating pressure in the system can be divided intotwo phases: in a first phase, a changed pressure range occurs since aswitch is made from a combination of valves on which pressure is exertedto another combination so that pressure accordingly has to be built up.Stationary phases occur between these switchover phases and no actionsare carried out in them. A stable pressure which is now measured inaccordance with the invention is present in these stationary operatingphases. In this connection, the respective pressure drop for thedifferent combinations is measured during the stationary operating phaseassociated with a specific combination and is transferred to anevaluation unit together with the measuring time. The pressure dropmeasured during such a stationary operating phase and the measuring timeare then associated with all those actuators on which pressure wasexerted during this specific combination. The leak tightness valueassociated with each actuator thus results in the course of theoperation from the averaged pressure drop of the combinations in whichthe respective actuator participated.

In FIGS. 1 to 4, different combinations of actuators on which pressureis exerted are shown for illustration. In this connection, the actuators1, 2, 3 are shown as representative for the usually considerably highernumber of actuators (e.g. 16 actuators) in a treatment machine on whichin each case pressure is exerted via apparatus 11, 12 and 13 or whichcan be cut off from the pressure supply. The apparatus 11, 12 and 13 areshown filled in in black in this connection when pressure is exerted onthe associated actuators 1, 2 or 3 or are colored white when no pressureis exerted on the corresponding actuators. In this connection, a centralpressure supply is provided for all the actuators on which pressure isexerted whose pressure can be determined using the pressure gage 5.

In FIG. 1, a first combination is shown in which pressure is exerted onall the actuators. In FIG. 2, in contrast, pressure is only exerted onactuator 1, whereas the actuators 2 and 3 are not active. In FIG. 3,pressure is exerted on the actuators 1 and 2, while the actuator 3 isnot active. In FIG. 4, actuator 1 is not active, while pressure isexerted on actuators 2 and 3.

It is now shown in the form of a table how the leak rate of theindividual actuators can be determined during the ongoing operation ofthe treatment machine by the measurement of the pressure drop and theassociation of the values to the actuators on which pressure isrespectively exerted. A valve pattern in the cassette results in thisconnection by acting on different combinations of actuators.

A specific common leak rate of the active actuators then results foreach combination from the respectively used combination of actuators onwhich pressure is exerted. The embodiment starts from a leak rate of theactuators 1 to 3 associated with the valves V1 to V3 of

V1: 5 mbar/minV2: 15 mbar/minV3: 0 mbar/min

In this connection, after a switching over of the actuator, it is firstwaited until a stationary operating state has been adopted. Thereupon,the pressure is measured in the embodiment for as long as thecorresponding combination is present. On a change of the valve patternwith a correspondingly new combination of actuators on which pressure isexerted, the pressure drop measured for the preceding combination issupplied together with the measuring time to an evaluation unit and ise.g. stored in a table, with the measured values only being associatedwith those actuators on which pressure is exerted in the correspondingcombination. Thereupon, the mean value of the measured values associatedwith the actuators is formed for all the actuators.

The leak tightness value associated with each actuator thus correspondsto the temporal mean value of the common pressure drop per time unit ofall previous combinations in which pressure was exerted on therespective actuator.

In the pattern 1 shown in Table 1, which corresponds to an arrangementin accordance with FIG. 1, pressure is exerted on all the actuators andall the valves V1 to V3 are accordingly closed. A common leak rate ofall actuators of 20 mbar/min hereby results. The pressure drop duringthe presence of pattern 1 is measured and is stored in the table,together with the then current measuring time for all participatingactuators. A switch is thereupon made to pattern 2 which corresponds toFIG. 2 and in which pressure is only exerted on actuator 1. A leak rateof 5 mbar/min hereby results. The corresponding pressure drop and themeasuring time are accordingly also only associated with actuator 1.With pattern 3, which corresponds to FIG. 3, pressure is then exerted onthe first two actuators, whereby a common leak rate of 20 mbar/minresults. The pressure drop which hereby arises is then stored in thetable together with the measuring times for the participating actuators1 and 2.

If now the total respective pressure drop associated with an actuator isdivided by the total measuring time associated with an actuator, a meanpressure drop per time unit results for each actuator. The morecombinations are taken into such a leak tightness value, the moreclosely the actual leak rate is approximated. In this connection,however, leaking valves can be recognized more clearly than leak tightvalves since the result of the leak tight valves is influenced by theleaking valves.

This can be recognized in the evaluation e.g. in accordance with pattern7 in which a leak rate of 10 mbar/min is associated with actuator 1, aleak rate of 16.7 mbar/min with actuator 2 and a leak rate of 5 mbar/minwith actuator 3.

The method shown in the table for the determination of the leaktightness values of the individual actuators can be implementedparticularly simply since the respectively measured pressure drop overthe duration of the stationary operating phases is associated in thesame way with all actuators on which pressure is exerted during thisoperating phase without the number of valves on which pressure isexerted being taken into account. The time average over all theoperating phases in which pressure was exerted on the actuator thenresults as the average value for each actuator. It is hereby ensuredthat the mean leak rate determined for every single actuator as the leaktightness value is always at least just as high as the actual leak rateof this actuator.

Alternatively, however, other mean value formations are also conceivablein which e.g. no averaging over time takes place, but rather thepressure drop per time unit which is determined for the differentcombinations of actuators, is taken into the end result in the samemanner in each case. It is equally conceivable to allow the number ofactuators on which pressure is exerted to flow into the averaging.

It is possible by the method in accordance with the invention also toensure a reliable recognition of leaks for a plurality of actuatorsduring the ongoing operation of the treatment machine. A typical numberof actuators e.g. amounts to 16. In accordance with the invention, all16 valves can thus be monitored via one single pressure gage during theongoing operation in that the pressure drop values determined duringdifferent combinations of switched actuators are respectively associatedwith the active actuators.

A result vector results in this connection in which the leak tightnessvalue is stored for each individual actuator and is updated in each caseon the change from one combination into another combination. Anapproximation to the actual total situation of the system thus resultsby the frequent repetition of the measuring method in accordance withthe invention with different patterns.

The result vector can then be further processed for the leakrecognition. The range of the leak rate can thus e.g. be determinedusing a minimum/maximum evaluation of the result vector. A narrow rangein which all the actuators have similar leak tightness rates is anindicator for a properly operating system. A wide range, in contrast,indicates a possible leak. Furthermore, a change in the leak behaviorcan be recognized using a sum evaluation of the result vector and itsgradient over time. A base leak rate of the system can equally bedetermined using a minimal value formation.

It is possible by the evaluation to recognize a defective actuator sincethis actuator causes an increased leak rate for every combination inwhich pressure is exerted on it. This is then reflected in the increasedaverage value for this actuator. It must be noted here that a trend canonly be recognized via the frequency of the individual measurements percomponent. Measurement imprecision phenomena which occur with fast valvepath changes and thus with fast changes of actuator combinations arefiltered in this process.

If the system discovers a leak tightness value for an actuator which isevaluated as an indicator for a leak, a test can additionally be carriedout to check the result. For this purpose, the operation of thetreatment device is interrupted and a test routine is carried out. Inthis connection, it can either be a known initial test in which all theactuators are checked. Alternatively, initially only the actuator or thegroup of actuators can also be checked in which the leak was recognizedbased on the corresponding leak tightness value which was outside apermitted range.

If an actuator has been identified as leaking, the treatment machine canchange into a safe state. If, however, sufficient alternatives for thedefective actuator are present, the operation can also be continuedwhile bypassing this actuator.

It is thus possible by the method in accordance with the invention tomonitor all the actuators with respect to their leak tightnessconstantly during the ongoing operation of the treatment machine and toreact as required.

TABLE Current Sum mea- Open −/ Current meas. Sum pres- suring EvaluationClosed + pressure time sure drop time Mbar/min: Pat- V1 + 20 mbar 1 min20 mbar 1 min 20 tern 1 V2 + 20 mbar 1 min 20 mbar 1 min 20 V3 + 20 mbar1 min 20 mbar 1 min 20 Pat- V1 + 25 mbar 5 min 45 mbar 6 min 7.5 tern 2V2 − — — 20 mbar 1 min 20 V3 − — — 20 mbar 1 min 20 Pat- V1 + 40 mbar 2min 85 mbar 8 min 10.6 tern 3 V2 + 40 mbar 2 min 60 mbar 3 min 20 V3 − —— 20 mbar 1 min 20 Pat- V1 − — — 85 mbar 8 min 10.6 tern 4 V2 + 15 mbar1 min 75 mbar 4 min 18.8 V3 + 15 mbar 1 min 35 mbar 2 min 17.5 Pat- V1 −— — 85 mbar 8 min 10.6 tern 5 V2 − — — 75 mbar 4 min 18.8 V3 +  0 mbar 5min 35 mbar 7 min 5 Pat- V1 +  5 mbar 1 min 90 mbar 9 min 10 tern 6 V2 −— — 75 mbar 4 min 18.8 V3 +  5 mbar 1 min 40 mbar 8 min 5 Pat- V1 − — —90 mbar 9 min 10 tern 7 V2 + 75 mbar 5 min 150 mbar  9 min 18.8 V3 − — —40 mbar 8 min 5

1-40. (canceled)
 41. A method of a monitoring leak-tightness of at leastone of an individual valve actuator and an individual group of valveactuators out of a plurality of pneumatically or hydraulically actuatedvalve actuators of a medical treatment machine, the medical treatmentmachine comprising a central pressure supply for the plurality of valveactuators, said method comprising the following steps: collecting aplurality of pressure drop values associated to a plurality of differentsub-groups of the plurality of valve actuators by determining, for eachsub-group, a pressure drop value, by performing, for each sub-group, thefollowing sub-steps: exerting pressure on the sub-group of valveactuators by connecting the sub-group of valve actuators to the centralpressure supply, and measuring a pressure drop value of the centralpressure supply associated to the sub-group; and determining aleak-tightness-value for the at least one of an individual valveactuator and an individual group of valve actuators on the basis of thefollowing sub-steps: determining a sub-set of the plurality of pressuredrop values, by determining, for each of the plurality of differentsub-groups, whether the individual valve actuator or the individualgroup of valve actuators formed part of the sub-group, and, if theindividual valve actuator or the individual group of valve actuatorsformed part of a sub-group, including a pressure drop value associatedto the sub-group in the sub-set, and determining theleak-tightness-value based on the sub-set of pressure drop values. 42.The method in accordance with claim 41, wherein the pressure drop ismeasured during a stationary operating phase of the associated sub-groupof valve actuators.
 43. The method in accordance with claim 41, whereinthe leak-tightness-value is additionally based on a measuring timeassociated to each out of the sub-set of pressure drop values.
 44. Themethod in accordance with claim 43, wherein the leak-tightness-value isdetermined on the basis of pressure drop per time unit values eachdetermined from a pressure drop value and an associated measuring time.45. The method in accordance with claim 43, wherein the measuring timefor a pressure drop value is chosen as the duration of a stationaryoperating phase of the associated sub-group of valve actuators for whichthe at least one of the pressure drop is measured.
 46. The method inaccordance with claim 41, wherein the step of determining the leaktightness value includes determining one out of a mean value over thesub-set of pressure drop values and a mean value over pressure drop pertime unit values associated to the sub-set of pressure drop values. 47.The method in accordance with claim 46, wherein the mean value is aweighted mean value.
 48. The method in accordance with claim 46, whereinthe step of determining the weighted mean value includes determining anumber of valve actuators in a sub-group of valve actuators.
 49. Themethod in accordance with claim 45, wherein the step of determining themean value includes determining, independently of the number of thevalve actuators in a sub-group of valve actuators, a measured pressuredrop for each sub-group of valve actuators.
 50. The method in accordancewith claim 41, wherein the step of determining the leak tightness valueincludes determining a pressure drop measured for each sub-group ofvalve actuators on which the pressure is exerted in equal amounts. 51.The method in accordance with claim 41, wherein the step of determiningthe leak tightness value includes continuously updating the leaktightness values of the at least one of the individual valve actuatorsand the individual groups of valve actuators during operation of themedical treatment machine.
 52. The method in accordance with claim 41,wherein a range of the determined leak tightness values is used formonitoring the valve actuators.
 53. The method in accordance with claim41, wherein a sum of all of the determined leak tightness values is usedfor monitoring the valve actuators.
 54. The method in accordance withclaim 41, wherein a change of the determined leak tightness values overtime is used for monitoring the valve actuators.
 55. The method inaccordance with claim 41, wherein operation of the medical treatmentmachine is stopped and a test is carried out on a recognition of a leak.56. The method in accordance with claim 41, wherein an initial test iscarried out in which all of the valve actuators are checked.
 57. Themethod in accordance with claim 55, wherein a test is carried out inwhich at least one of the individual valve actuators and the individualgroups of valve actuators in which a leak was recognized is checked. 58.The method in accordance with claim 41, wherein upon at least one of arecognition and a confirmation of a leak, the valve actuator that isleaking is no longer used or the medical treatment machine changes intoa safe state.
 59. The method in accordance with claim 41, wherein themethod controls the valve actuators associated with valves of a cassettefor the transport of a medical liquid.
 60. The method in accordance withclaim 41, wherein said steps of collecting and determining are effectedwhile said medical treatment machine is in communication with a patientto whom said medical treatment is being provided.
 61. A medicaltreatment machine comprising: a plurality of pneumatically orhydraulically actuatable valve actuators, a central pressure supply thatprovides the plurality of valve actuators with pressure, a pressure gagefor measurement of the pressure of the central pressure supply, and anelectronic control which controls the valve actuators by connecting themto the central pressure supply, wherein the electronic control collectsa plurality of pressure drop values associated to a plurality ofdifferent sub-groups of the plurality of valve actuators by determining,for each sub-group, a pressure drop value, by performing, for eachsub-group, the following sub-steps: exerting pressure on the sub-groupof valve actuators by connecting the sub-group of valve actuators to thecentral pressure supply, and measuring a pressure drop value of thecentral pressure supply associated to the sub-group; an evaluation unitwhich determines a leak-tightness-value for at least one of anindividual, valve actuator and an individual group of valve actuators byperforming the following sub-steps: determining a sub-set of theplurality of pressure drop values, by determining, for each of theplurality of different sub-groups, whether the individual valve actuatoror the individual group of valve actuators formed part of the sub-group,and if the individual, valve actuator or the individual group of valveactuators formed part of a sub-group, including a pressure drop valueassociated to the sub-group in the sub-set, and determining theleak-tightness-value based on the sub-set of pressure drop values, and amonitoring unit that monitors the leak tightness of the valve actuatorsof the medical treatment machine based on the determined leak tightnessvalues.
 62. The medical treatment machine in accordance with claim 61,wherein the control unit collects a measuring time associated to eachpressure drop value.
 63. The medical treatment machine in accordancewith claim 61, wherein the control unit measures a pressure drop valueassociated to a sub-group of valve actuators for a duration of astationary operating phase of the associated sub-group of valveactuators.
 64. The medical treatment machine in accordance with claim61, wherein, for determining a leak tightness value, the machinedetermines a pressure drop per time unit value calculated from ameasured pressure drop value and an associated measuring time.
 65. Themedical, treatment machine in accordance with claim 61, wherein theevaluation unit determines one out of a mean value over the sub-set ofpressure drop values and a mean value over pressure drop per time unitvalues associated to the sub-set of pressure drop values.
 66. Themedical treatment machine in accordance with claim 65, wherein meanvalue is a weighted mean value.
 67. The medical treatment machine inaccordance with claim 56, wherein for determining the weighted meanvalue, the evaluation unit determines a number of valve actuators in asub-group of valve actuators.
 68. The medical, treatment machine in,accordance with claim 65, wherein for determining the mean value, theevaluation unit determines, independently of the number of the valveactuators in a sub-group of valve actuators, a measured pressure dropfor each sub-group of valve actuators.
 69. The medical treatment machinein accordance with claim 61, wherein the evaluation unit determines asum of all pressure drop values in the sub-set of pressure drop valuesand a sum of associated measuring times.
 70. The medical treatmentmachine in accordance with claim 61, wherein the evaluation unitcontinuously updates the leak tightness values of at least one of theindividual valve actuators and the individual groups of valve actuatorsduring operation of the medical treatment machine.
 71. The medicaltreatment machine in accordance with claim 61, wherein the monitoringunit monitors the leak tightness of the valve actuators based on a rangeof the determined leak tightness values.
 72. The medical treatmentmachine in accordance with claim 61, wherein the monitoring unitmonitors the leak tightness of the valve actuators based on a sum of allof the determined leak tightness values.
 73. The medical treatmentmachine in accordance with claim 61, wherein the monitoring unitmonitors the leak tightness of the valve actuators based on a changeover time of the determined leak tightness values.
 74. The medicaltreatment machine in accordance with claim 61, wherein the monitoringunit stops operation of the medical treatment machine on a recognitionof a leak, and carries out a test.
 75. The medical treatment machine inaccordance with claim 61, wherein the monitoring unit carries out aninitial test in which all of the valve actuators are checked.
 76. Themedical treatment machine in accordance with claim 74, wherein themonitoring unit carries out a test in which at least one of theindividual valve actuators and the individual groups of valve actuatorsfor which a leak was recognized is checked.
 77. The medical treatmentmachine in accordance with claim 61, wherein the electronic control,upon at least one of a recognition and a confirmation of a leak, nolonger uses the valve actuator that is leaking or switches the medicaltreatment machine into a safe state.
 78. The medical treatment machinein accordance with claim 61, wherein the valve actuators are associatedwith valves of a cassette for the transport of a medical liquid.
 79. Themedical treatment machine in accordance with claim 78, furthercomprising a coupling surface to which a cassette can be coupled for thetransport of a medical liquid, with the valve actuators being arrangedat the coupling surface.
 80. The medical treatment machine according toclaim 61, further comprising a non-transitory computer readable mediumfor the monitoring of the leak tightness of the valve actuators.
 81. Themedical treatment machine in accordance with claim 61, wherein themedical treatment machine is for dialysis.
 82. The medical treatmentmachine in accordance with claim 61, said medical treatment machinebeing configured such that the exerting of the pressure, the measuringof the pressure drop values, and the determining of the leak tightnessvalue are performed while a medical treatment is being effected with themedical treatment.